In the field of high-speed printing devices which are especially suitable for use in connection with electronic business systems, the wire matrix type of printer has come into increasing use. In this type of printer, letters, numbers and symbols are formed from a series of dots produced by the impact of the ends of a plurality of wire elements on record media, most customarily in combination with an ink ribbon which provides the ink needed to produce a mark on the record medium being printed upon.
Customarily each of the individual wire printing elements of a wire matrix printer is driven by a solenoid which is energized when a printing stroke of that wire is required. Since all of the solenoids are normally coupled to a single power supply, and since the number of solenoids driven to produce a print for a particular character or portion of a character may differ substantially from one time to the next, it will be understood that some variation in the voltages applied to the solenoids from the power supply may result. If not corrected in some way, this variation of voltage is likely to result in variation of the energy applied to the wire elements by energization of the solenoids, with the consequence of a non-uniform appearance in the printing on the record medium.